1 #include "alloc.h"

     2 #include "error.h"

     3 extern char *malloc();

     4 extern void free();

     5 

     6 #define ALIGNMENT 16 /* XXX: assuming that this alignment is enough */

     7 #define SPACE 4096 /* must be multiple of ALIGNMENT */

     8 

     9 typedef union { char irrelevant[ALIGNMENT]; double d; } aligned;

    10 static aligned realspace[SPACE / ALIGNMENT];

    11 #define space ((char *) realspace)

    12 static unsigned int avail = SPACE; /* multiple of ALIGNMENT; 0<=avail<=SPACE */

    13 

    14 /*@null@*//*@out@*/char *alloc(n)

    15 unsigned int n;

    16 {

    17   char *x;

    18   n = ALIGNMENT + n - (n & (ALIGNMENT - 1)); /* XXX: could overflow */

    19   if (n <= avail) { avail -= n; return space + avail; }

    20   x = malloc(n);

    21   if (!x) errno = error_nomem;

    22   return x;

    23 }

    24 

    25 void alloc_free(x)

    26 char *x;

    27 {

    28   if (x >= space)

    29     if (x < space + SPACE)

    30       return; /* XXX: assuming that pointers are flat */

    31   free(x);

    32 }